I've been tossing my egg shells to the birds for years. Initially, I was rinsing them to get all of the albumen out of them, drying them, then heating in microwave or oven, then crushing them very fine. Then, I decided it was a waste to wash all of the protein of any albumen out of the shells and simply dried them, heated them, and crushed them. Then... for the last 2 years, I simply toss the shells into a bowl. When I head out to the coop, I grab the bowl, toss the shells in the run, stomp on them, and continue on my merry way. My girls eat the shells. No egg eaters here. No issues with bacterial contamination. You will hear everything from: "never give egg shells to your birds. It will turn them into egg eaters." "The shells must be finely ground up so your birds will not be able to tell that they are egg shells, and they must have all of the albumen rinsed out of them, and be sterilized so your birds don't get sick." to: "It's a waste of time to give egg shells to chickens b/c they can't absorb the calcium from them". All of these statements are false. So, IMO it's simply good sense to turn those shells over to the birds so they can recycle the nutrients in them.